Mast joint for telescopic masts



p 1955 L. MIDDLEDIT CH, JR

MAST JOINT FOR TELESCOPIC MASTS Filed July 3, 1951 INVENTOR.

LYMAN MIDDLEDITCHQR.

fl aA fiy A o /hy United States Patent 6 MAST JOINT FOR TELESCOPIC MASTS Lyman Middleditch, Jr., Shrewsbury, N. J., assignor to the United States of America as represented by the Secretary of the Army Application July 3, 1951, Serial No. 235,080

9 Claims. 1 (Cl. 189-26) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

.T his invention relates to improvements in mast joints for telescopic masts of the type or class adapted more particularly for supporting radio antennas or the like in elevated position.

An example of a telescopic mast belonging to the same general class as that of the present improved mast is shown and described in Patent No. 1,581,325 issued April 20, 1926, to Russell J. Sands.

One of the objects of the present invention is the provision of an improved mast of the character referred to which can be rapidly assembled or easily collapsed, if desired, which is economical to make,'and in which the complementary and coacting joint structures of the respective adjacent ends of adjacent sections of the extended mast provide for a rigid, durable and fluid-tight joint between such sections. Another object of the present invention is the provision of an improved mast composed of sections, each section having thesame length, and each being capable of totally enclosing its complementary section when in the collapsed position.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating the invention, an embodiment thereof is shown in the drawings, wherein Figs. 1 and 2 are elevational views of two mast sections which are adjacent to and are joined together when the mast is extended or erected, and which are moved into telescopic relation, one within the other, when the mast is collapsed;

Fig. 3 is an enlarged, fragmentary, sectional view, the section being taken on the line 3-3 in Fig. 1;

Fig. 4 is a fragmentary view, looking toward the left in Fig. 3;

Fig. 5 is a sectional view taken on the line 5-5 in Fig. 3;

Figs. 6 and 7 are views similar to Fig. 3 and illustrative, respectively, of different stages in the operating action which takes place in erecting or setting up the mast;

Figs. 8 and 9 are fragmentary views looking toward the left in Fig. 7 and illustrative, respectively, of two succeeding positions which adjacent parts take,'relativelywith respect to each other, in tightening or completing ajoint between adjacent mast sections;

Figs. 10 and 11 are fragmentary views corresponding, respectively, to Figs. 1 and 2 and illustrative of a modification;

Fig. 12 is a sectional view, the section being taken on the line 12-12 in Fig. 10;

Fig. 13 is an elevational view of an extended and setup telescopic mast constructed and operating in accordance with the present invention; I

Fig. 14 is an enlarged, vertical, sectional view showing the mast sections in Fig. 13 partially collapsed; and

Figs. 15 and 16 show a modification and correspond, respectively, to Figs. 3 and 4.

Adjacent sections 10 and 11 of the improved mast are Patented Sept. 27, 1955 shown in detail in Figs. 1 and 2, respectively. In Fig. 13, the adjacent and respective extremities 10a and 11a of these sections are shown joined together as part of an extended telescopic mast of the type shown and described in the patent aforesaid.

The extremity 10a integral with section 10 has a slight taper and is complementary to the extremity 11a integral with section 11 and having a slight taper, similar to that of extremity 10a. Each of the sections 10 and 11 is in the form of an elongated tubular part which may be made of plywood, steel, aluminum, or other material suitable for the manufacture of tubing. I

To extremity 10a there is fixed, by rivets 12 or in any other suitable manner, a latch piece 14 which may be stamped out of sheet-metal material of spring steel or the equivalent. If rivets are used, both ends of each are filed or ground down to be flush with the respective outside and inside surfaces 14a and 10b. The free end of latch 14 is bent or curled back, as more clearly shown in Fig. 3, to form a hook 14b which extends through a hole in extremity 10a and which is normally disposed partly Within the tubular part 10, away or spaced from the inside surface 10b of extremity 10a.

The tapered extremity 11a of section 11 is provided with a cam surface by cutting or otherwise shaping the wall structure of this section to form a sloping cam edge 11b.

To secure or join the mast sections 10 and 11, as would be done in erecting or setting up a telescopic mast of similar sections requisite in number for the particular height or elevation desired, the extremity 11d of section 11 is inserted into the larger and similarly tapered extremity 10d of section 10, and the section 11 is then pushed along, to be entirely within section 10. For such purpose, the outside diameter of the intermediate cylindrical part 11e of section 11 is made slightly less than the inside diameter of the intermediate cylindrical part 10e of section 10. As shown in Fig. 6, in passing through section 10 the leading edge 11f of section 11 engages hook 14b of latch 14 to flex or springthe latter radially outwardly and flush with surface 10b. With section 11 now entirely within section 10, and section 11 being substantially the same length as section 10, the index finger can now be inserted into the extremity 11d of section 11 to move the latter further along so that extremity 11d protrudes from extremity 10a and can be grasped. Taking a firm hold on extremity 11d of section 11, the operator now pulls this section out of section 10 until section 11 is in the fullyextended position with respect to section 10, as shown in Fig. 13. As section 11 reaches its fully-extended position, the tapered extremity 11a thereof becomes wedged into the complementary and similarly-tapered extremity 10a of section 10, and the two sections are joined.

To tighten and securely lock the joint between sections 10 and 11, is the function of latch 14 and cam edge 11b. The disposition of latch 14 is such that just before extremity 11a of section 11 becomes firmly wedged into extremity 10a of section 10, the low end 11g of cam edge 11b is in the same plane as the edge of hook 14b, such plane being considered perpendicular to the longitudinal axis of section 11. As clearly illustrated in Figs. 1 and 2, only one end of cam 11b, namely low end 11g, is substantially in alignment with the latch opening at the other extremity of section 11. A similar arrangement is, of course, provided for other sections of the mast. Hook 14b, accordingly, is released and moves radially inwardly with a snap action to the position shown in Figs. 7 and 8. To tighten the joint, section 11 is rotated relatively with respect to section 10 about the longitudinal axis common to these sections, and in the direction to bring cam edge 11!; to a position further to the right with respect to hook 14b, as shown in Fig. 9. The slope of cam edge 11b being as shown in Figs. 2, 8 and 9, this final tightening action or movement causes an increasing force to be exerted on latch 14 in the direction longitudinally of the sections and 11, similarly to the respective and corresponding forces on screw-threads when tightening a nut onto a bolt. In the present case the action, specifically, causes to be exerted and maintained strong and equal and oppositelydirected forces urging sections 10 and 11 further apart or away from each other, as viewed in Fig. 13 and against the restraining action of the complementary and similarlytapered extremities 10a and 11a wedged tightly, one within the other.

The considerations for determining the slope and configuration of cam edge 11]) and its length measured around the edge of extremity 11a, are the same as those for determining the pitch, shape and number of threads in a design utilizing a screw-thread action.

In the operation or steps just explained for extending and locking the two sections 10 and 11 in tightly joined relation, it might occur that the parts do not assume the respective positions thereof as shown in Figs. 7 and 8 because the hook 14b, looking into the tubular sections, does not register with the low end 11g of cam edge 11b or is entirely out of registration with the cam edge. Hook 14b is therefore still engaged with and restrained by the outside surface of extremity 11a. In such event, section 11 is rotated as before until the low end of 11g of cam edge 11b registers with hook 14b to permit the latter to snap inwardly to the position shown in Figs. 7 and 8.

i To break or disassemble the improved mast joint between sections 10 and 11, section 11 is rotated in the direction opposite to that aforesaid, whereupon the surface 14h, disposed at an angle to the surface of member 14, of hook 14b is engaged by the cam surface 11i of a relatively small part 11 of the wall of extremity 11a. This wall part 11 is disposed at the low end 11g of cam edge 11b, and is bent inwardly into the mast section 11. This reverse or opposite rotation of section 11 is continued until the cam action of part 11 on hook 14b forces the latter radially outwardly to move latch 14 out of latching position and clear of cam edge 11b, or in other words, so that the inner extremity of edge 140 of hook 14b is flush with surface 1%. Section 11 is then free to be pushed into section 10 to the collapsed or partly collapsed position as shown in Fig. 14.

In lieu of making the latch as a separate piece riveted or otherwise secured to extremity 1011, it may be struck out from the wall of this extremity, as shown in Figs. 15 and 16 wherein the struck-out latch 14 is shaped and functions in the same manner and for the same purpose as latch 14 in Figs. 1 and 3 to 9.

The extremity 10a may be provided with two or more of the latches 14, uniformly spaced around the former. In such case, the extremity 11a is provided with the same number of cam edges 11b uniformly spaced around extremity 11a.

Instead of tapering the respective complementary extremities of adjacent mast sections, as in Figs. 1 and 2, these may be made cylindrical as shown in Figs. 10 and 11 wherein the section 11' corresponds to section 11 in Fig. 2 and the section 10' corresponds to section 10 in Fig. 1. In such a modification, a -chamfer 15 in section 11' engages the inwardly protruding heads of rivets 16 in extremity 10 just after hook 14b snaps inwardly for its joint-tightening coaction with cam surface 11b. Otherwise the construction and operating action is the same as in Figs. 1 to 9.

To facilitate disassembly of adjacent mast sections, it is proposed to apply a suitable lubricant to the inside surface of extremity 10a and to the outside surface of extremity 11a before these sections are joined.

Assuming that the improved mast is collapsed or partly collapsed as shown in Fig. 14, to erect the same the two end sections 10 and 17 are pulled in diametrically-opposite directions to extend the mast to substantially its full length, and the mast so extended is laid out on the ground.

The joint between sections 10 and 11 may then be completed as explained, after which the joint between section 11 and its adjacent section 18 may be likewise completed, and so on to the top section 17.

When the mast is erected, the bottom end or extremity of section 10 is inserted into a cup-shaped base shoe 18 corresponding to and serving the same purpose as the supporting bracket E in the Sands patent aforesaid. The shoe 18 may be anchored by a spike 19 sunk into the ground and connected to the shoe by a chain 20. A bolt or pin 21 through registering holes in section 10 and shoe 18 fix the mast against accidental dislodgment from the shoe.

It will be understood that various modifications such as in the size, shape and arrangement of the parts, are possible without departing from the spirit of the invention or the scope of the claims.

The invention claimed is:

1. As an article of manufacture, a section for a telescopic mast comprising sections each of which is complementary to, and joined to, an adjacent section when the mast is extended and each of which is movable into telescopic relation with an adjacent section when the mast is collapsed; said section comprising an elongated tubular part provided at one extremity thereof with a sloping cam edge the surface of which is formed by a side of a notch cut into said tubular part, a relatively small portion of the wall of said tubular part at an end of said cam edge being bent inwardly into said tubular part and shaped and disposed to provide a cam surface protruding radially inwardly from the wall of said tubular part.

2. As an article of manufacture, a section for a tele scopic mast which comprises a plurality of sections each of which is complementary to, and joined to, an adjacent section when the mast is extended and each of which is movable into telescopic relation with an adjacent section when the mast is collapsed; each of said plurality of sections comprising an elongated tubular part having one extremity tapered and provided with an opening, and a latch disposed at said one extremity and fixed thereto against movement in the direction longitudinally of said part, said one extremity being tapered so as to provide a space for said latch, thereby enabling the sections to be telescoped into an adjacent section when the mast is collapsed, said latch extending through said opening and into said tubular part and being movable with respect thereto in the direction radially outwardly thereof, said latch being normally disposed at least partly within said tubular part away from the inside surface of the latter, the other extremity of said elongated tubular part being similarly tapered and provided with a sloping cam edge, the surface of which is formed by one side of a notch cut out of said tubular part at said other extremity and extending only part way around the same, one end only of said sloping cam edge being substantially in alignment with said opening at said other extremity.

3. An article of manufacture according to claim 1, wherein at least one extremity of said section is at least partially tapered.

4. An article of manufacture according to claim 3, wherein said section is provided with an opening at the other extremity thereof, and including a latch fixedly disposed at said other extremity, said latch having one end shaped in the form of a hook extending through said opening and into said section adapted to engage the cam edge of an adjacent section when the mast is extended.

5. An article of manufacture according to claim 4, wherein said other extremity is provided with at least one inwardly protruding projection.

6. A telescopic mast comprising a plurality of longitudinal sections, each of which is complementary to, and joined to, an adjacent section when the mast is extended and each of which is movable into telescopic relation with an adjacent section when the mast is collapsed, each of said sections comprising a cam surface disposed at one end and extending at least part way around the same, and a latch aflixed to the other end adapted to latch onto and engage the cam surface of an adjacent complementary section when the mast is extended, the latch end of each one of said sections being sufliciently larger than the latch end of an adjacent section to provide a space for entry of the latch of said adjacent section into the latch end of said one section when said sections are telescoped, the adjacent ends of said one section and of said adjacent complementary section being similarly tapered, said adjacent ends thereby engaging each other and providing a wedge joint to prevent further extension when said mast is extended, the slope of said cam surface being in a direction to exert an increasing longitudinal force on its corresponding latch incident to rotation in a given direction of one of said sections relative to said adjacent complementary section about the longitudinal axis of said sections, said latch further including an angularly disposed surface, and means disposed at an end of said cam surface for engagement with said angularly disposed surface of said latch incident to rotation in a direction opposite to said given direction of each of said sections relative to said adjacent complementary section, said means serving to disengage its corresponding cam surface and latch, thereby moving the latch out of latching position and clear of its associated cam surface.

7. A telescopic mast comprising a plurality of longitudinal sections each of which is complementary to, and joined to, an adjacent section when the mast is extended and each of which is movable into telescopic relation with an adjacent section when the mast is collapsed, the adjacent extremities of said sections being similarly tapered and constituting joints therebetween when said mast is extended, the wall of one of said extremities at each joint being shaped to provide a sloping cam edge, a relatively small portion of the wall at one end of said cam edge being bent inwardly of said wall, the other of said extremities at each joint being provided with an opening, and a latch respectively fixed at one end thereof to the outside of said other of said extremities, the other end of said latch being shaped in the form of a hook extending through said opening and being latched around and engaging said one end of said cam edge, the slope of each cam edge being in a direction to exert an increasing longitudinal force on its associated latch incident to rotation about the longitudinal axis of said sections in a given direction of each of said sections relative to an adjacent section, said hook end of said latch including an angularly disposed surface so that rotation about the longitudinal axis of said sections in a direction opposite to said given direction of each one of said sections relative cam edge from said hook.

8. An article of manufacture according to claim 3 further including a latch means struck out of the other extremity of said section, said latch means having one end extending into said section and shaped to hook the cam edge of an adjacent section when the mast is extended.

9. A telescopic mast comprising a plurality of longitudinal sections each of which is complementary to, and joined to, an adjacent section when the mast is extended and each of which is movable into telescopic relation with an adjacent section when the mast is collapsed, the adjacent extremities of said sections when said mast is extended being similarly tapered and constituting wedge joints therebetween, the wall of one of said tapered extremities at each joint being shaped to provide a sloping cam edge, the other of said extremities at each joint being provided with an opening, and a latch fixed at one end thereof to the outside of said other of said extremities, the other end of said latch being shaped in the form of a hook extending through said opening and latched around and engaging said cam edge, the slope of said cam edge being in a direction to exert an increasing longitudinal force on said latch incident to rotation in a given direction of each one of said sections relative to an adjacent section about the longitudinal axis of said sections, an end of said cam edge being bent inwardly into its respective mast section and shaped and disposed for engagement with said latch incident to rotation in a direction opposite to said given direction of its section relative to an adjacent section, said cam end serving to disengage said latch thereby moving said latch out of latching position and clear of said cam edge.

References Cited in the file of this patent UNITED STATES PATENTS 123,776 Goodale Feb. 20, 1872 264,243 Chubb Sept. 12, 1882 616,311 Gracey Dec. 20, 1898 729,479 Wittman May 26, 1903 930,406 McDonald Aug. 10, 1909 995,893 Neitzel June 20, 1911 1,121,147 Stiglich Dec. 15, 1914 1,581,325 Sands Apr. 20, 1926 2,436,763 Wing Feb. 24, 1948 FOREIGN PATENTS 279,691 Great Britain Nov. 3, 1927 946,465 France Dec. 20, 1948 

